Handwork in Wood Part 11

Sc.r.a.ping tools are of such nature that they can only abrade or smooth surfaces.

[Ill.u.s.tration: Fig. 142. Auger-Bit-File.]

[Ill.u.s.tration: Fig. 143. Single-Cut Blunt, Flat, b.a.s.t.a.r.d File.]

[Ill.u.s.tration: Fig. 144. Three-Square Single-Cut File.]

[Ill.u.s.tration: Fig. 145. Open Cut, Taper, Half-Round File.]

[Ill.u.s.tration: Fig. 146. Double-Cut File.]

[Ill.u.s.tration: Fig. 147. Cabinet Wood-Rasp.]

[Ill.u.s.tration: Fig. 148. File-Card.]

_Files._ Figs. 142-146, are formed with a series of cutting edges or teeth. These teeth are cut when the metal is soft and cold and then the tool is hardened. There are in use at least three thousand varieties of files, each of which is adapted to its particular purpose. Lengths are measured from point to heel exclusive of the tang. They are cla.s.sified: (1) according to their outlines into blunt, (i. e., having a uniform cross section thruout), and taper; (2) according to the shape of their cross-section, into flat, square, three-square or triangular, knife, round or rat-tail, half-round, etc.; (3) according to the manner of their serrations, into single cut or "float" (having single, unbroken, parallel, chisel cuts across the surface), double-cut, (having two sets of chisel cuts crossing each other obliquely,) open cut, (having series of parallel cuts, slightly staggered,) and safe edge, (or side,) having one or more uncut surfaces; and (4) according to the fineness of the cut, as rough, b.a.s.t.a.r.d, second cut, smooth, and dead smooth. The "mill file," a very common form, is a flat, tapered, single-cut file.

[Ill.u.s.tration: Fig. 149. a. Diagram of a Rasp Tooth. b. Cross-Section of a Single-Cut File.]

_Rasps_, Fig. 147, differ from files in that instead of having cutting teeth made by lines, coa.r.s.e projections are made by making indentations with a triangular point when the iron is soft. The difference between files and rasps is clearly shown in Fig. 149.

It is a good rule that files and rasps are to be used on wood only as a last resort, when no cutting tool will serve. Great care must be taken to file flat, not letting the tool rock. It is better to file only on the forward stroke, for that is the way the teeth are made to cut, and a flatter surface is more likely to be obtained.

Both files and rasps can be cleaned with a _file-card_, Fig. 148. They are sometimes sharpened with a sandblast, but ordinarily when dull are discarded.

[Ill.u.s.tration: Fig. 150. Molding-Sc.r.a.pers.]

_Sc.r.a.pers_ are thin, flat pieces of steel. They may be rectangular, or some of the edges may be curved. For sc.r.a.ping hollow surfaces curved sc.r.a.pers of various shapes are necessary. Convenient shapes are shown in Fig. 150. The cutting power of sc.r.a.pers depends upon the delicate burr or feather along their edges. When properly sharpened they take off not dust but fine shavings. Sc.r.a.pers are particularly useful in smoothing cross-grained pieces of wood, and in cleaning off glue, old varnish, etc.

There are various devices for holding sc.r.a.pers in frames or handles, such as the sc.r.a.per-plane, Fig. 111, p. 79, the veneer-sc.r.a.per, and box-sc.r.a.pers. The _veneer-sc.r.a.per_, Fig. 151, has the advantage that the blade may be sprung to a slight curve by a thumb-screw in the middle of the back, just as an ordinary sc.r.a.per is when held in the hands.

In use, Fig. 152, the sc.r.a.per may be either pushed or pulled. When pushed, the sc.r.a.per is held firmly in both hands, the fingers on the forward and the thumbs on the back side. It is tilted forward, away from the operator, far enough so that it will not chatter and is bowed back slightly, by pressure of the thumbs, so that there is no risk of the corners digging in. When pulled the position is reversed.

[Ill.u.s.tration: Fig. 151. Using a Veneer-Sc.r.a.per.]

One method of sharpening the sc.r.a.per is as follows: the sc.r.a.per is first brought to the desired shape, straight or curved. This may be done either by grinding on the grindstone or by filing with a smooth, flat file, the sc.r.a.per, while held in a vise. The edge is then carefully draw-filed, i. e., the file, a smooth one, is held (one hand at each end) directly at right angles to the edge of the sc.r.a.per, Fig.

153, and moved sidewise from end to end of the sc.r.a.per, until the edge is quite square with the sides. Then the sc.r.a.per is laid flat on the oilstone and rubbed, first on one side and then on the other till the sides are bright and smooth along the edge, Fig. 154. Then it is set on edge on the stone and rubbed till there are two sharp square corners all along the edge, Fig. 155. Then it is put in the vise again and by means of a burnisher, or sc.r.a.per steel, both of these corners are carefully turned or bent over so as to form a fine burr. This is done by tipping the sc.r.a.per steel at a slight angle with the edge and rubbing it firmly along the sharp corner, Fig. 156.

[Ill.u.s.tration: Fig. 152. Using a Cabinet-Sc.r.a.per.]

To resharpen the sc.r.a.per it is not necessary to file it afresh every time, but only to flatten out the edges and turn them again with slightly more bevel. Instead of using the oilstone an easier, tho less perfect, way to flatten out the burr on the edges is to lay the sc.r.a.per flat on the bench near the edge. The sc.r.a.per steel is then pa.s.sed rapidly to and fro on the flat side of the sc.r.a.per, Fig. 157.

After that the edge should be turned as before.

[Ill.u.s.tration: Fig. 153. Sharpening a Cabinet-Sc.r.a.per: 1st Step, Drawfiling.]

_Sandpaper._ The "sand" is crushed quartz and is very hard and sharp.

Other materials on paper or cloth are also used, as carborundum, emery, and so on. Sandpaper comes in various grades of coa.r.s.eness from No. 00 (the finest) to No. 3, indicated on the back of each sheet. For ordinary purposes No. 00 and No. 1 are sufficient. Sandpaper sheets may readily be torn by placing the sanded side down, one-half of the sheet projecting over the square edge of the bench. With a quick downward motion the projecting portion easily parts. Or it may be torn straight by laying the sandpaper on a bench, sand side down, holding the teeth of a back-saw along the line to be torn. In this case, the smooth surface of the sandpaper would be against the saw.

[Ill.u.s.tration: Fig. 154. Sharpening a Cabinet-Sc.r.a.per: 2nd Step, Whetting.]

[Ill.u.s.tration: Fig. 155. Sharpening a Cabinet-Sc.r.a.per: 3rd Step, Removing the Wire-Edge.]

Sandpaper should never be used to sc.r.a.pe and scrub work into shape, but only to obtain an extra smoothness. Nor ordinarily should it be used on a piece of wood until all the work with cutting tools is done, for the fine particles of sand remaining in the wood dull the edge of the tool. Sometimes in a piece of cross-grained wood rough places will be discovered by sandpapering. The surface should then be wiped free of sand and sc.r.a.ped before using a cutting tool again. In order to avoid cross scratches, work should be "sanded" with the grain, even if this takes much trouble. For flat surfaces, and to touch off edges, it is best to wrap the sandpaper over a rectangular block of wood, of which the corners are slightly rounded, or it may be fitted over special shapes of wood for specially shaped surfaces. The objection to using the thumb or fingers instead of a block, is that the soft portions of the wood are cut down faster than the hard portions, whereas the use of a block tends to keep the surface even.

[Ill.u.s.tration: Fig. 156. Sharpening a Cabinet-Sc.r.a.per: 4th Step, Turning the Edge.]

_Steel wool_ is made by turning off fine shavings from the edges of a number of thin discs of steel, held together in a lathe. There are various grades of coa.r.s.eness, from No. 00 to No. 3. Its uses are manifold: as a subst.i.tute for sandpaper, especially on curved surfaces, to clean up paint, and to rub down sh.e.l.lac to an "egg-sh.e.l.l"

finish. Like sandpaper it should not be used till all the work with cutting tools is done. It can be manipulated until utterly worn out.

5. POUNDING TOOLS.

The _hammer_ consists of two distinct parts, the head and the handle.

The head is made of steel, so hard that it will not be indented by hitting against nails or the b.u.t.t of nailsets, punches, etc., which are comparatively soft. It can easily be injured tho, by being driven against steel harder than itself. The handle is of hickory and of an oval shape to prevent its twisting in the hand.

[Ill.u.s.tration: Fig. 157. Resharpening a Cabinet-Sc.r.a.per: Flattening the Edge.]

Hammers may be cla.s.sified as follows: (1) hammers for striking blows only; as, the blacksmith's hammer and the stone-mason's hammer, and (2) compound hammers, which consist of two tools combined, the face for striking, and the "peen" which may be a claw, pick, wedge, shovel, chisel, awl or round head for other uses. There are altogether about fifty styles of hammers varying in size from a jeweler's hammer to a blacksmith's great straight-handled sledge-hammer, weighing twenty pounds or more. They are named mostly according to their uses; as, the riveting-hammer, Fig. 159, the upholsterer's hammer, Fig. 160, the veneering-hammer, Fig. 162, etc. Magnetized hammers, Fig. 161, are used in many trades for driving brads and tacks, where it is hard to hold them in place with the fingers.

[Ill.u.s.tration: Fig. 158. Claw-Hammer.]

[Ill.u.s.tration: Fig. 159. Riveting-Hammer.]

[Ill.u.s.tration: Fig. 160. Upholster's Hammer.]

[Ill.u.s.tration: Fig. 161. Magnetized Hammer.]

[Ill.u.s.tration: Fig. 162. Veneering-Hammer.]

In the "bell-faced" hammer, the face is slightly convex, in order that the last blow in driving nails may set the nail-head below the surface. It is more difficult to strike a square blow with it than with a plain-faced hammer. For ordinary woodwork the plain-faced, that is, flat-faced claw-hammer, Fig. 158, is best. It is commonly used in carpenter work.

It is essential that the face of the hammer be kept free from glue in order to avoid its sticking on the nail-head and so bending the nail.

Hammers should be used to hit iron only; for hitting wood, mallets are used. In striking with the hammer, the wrist, the elbow and the shoulder are one or all brought into play, according to the hardness of the blow. The essential precautions are that the handle be grasped at the end, that the blow be square and quick, and that the wood be not injured. At the last blow the hammer should not follow the nail, but should be brought back with a quick rebound. To send the nail below the surface, a nailset is used. (See below.)

[Ill.u.s.tration: Fig. 163. Drawing a Nail with Claw-Hammer.]

The claw is used for extracting nails. To protect the wood in withdrawing a nail a block may be put under the hammer-head. When a nail is partly drawn, the leverage can be greatly increased by continuing to block up in this way, Fig. 163.

[Ill.u.s.tration: Fig. 164. Mallets.]

The _mallet_, Fig. 164, differs from the hammer in having a wooden instead of a steel head. A maul or beetle is a heavy wooden mallet.

The effect of the blow of a mallet is quite different from that of a hammer, in that the force is exerted more gradually; whereas the effect of the hammer blow is direct, immediate, and local, and is taken up at once. But a mallet continues to act after the first impulse, pushing, as it were. This is because of the elasticity of the head. A chisel, therefore, should always be driven with a mallet, for the chisel handle would soon go to pieces under the blows of a hammer, because of their suddenness; whereas the mallet blow which is slower will not only drive the blade deeper with the same force, but will not injure the handle so rapidly. Mallet-heads are made square, cylindrical, and barrel-shaped. Carver's mallets are often turned from one piece, hammer and head on one axis.

_Nailsets_, Fig. 165, are made with hardened points, but softer b.u.t.ts, so that the hammer will not be injured. They were formerly made square when nail heads were square, but now round ones are common. To obviate slipping, some have "cup points," that is, with a concave tip, and some spur points.

[Ill.u.s.tration: Fig. 165. Using a Nailset.]

To keep the nailset in its place on the nail-head it may be held closely against the third finger of the left hand, which rests on the wood close to the nail. When a nailset is lacking, the head of a brad, held nearly flat, may be used. But care is necessary to avoid bruising the wood.